1. Field of the Invention
The present invention relates to an electrophotographic apparatus, in particular, to an electrophotographic apparatus such as a copying machine, a plane paper facsimile device, a printer, or the like.
2. Discussion of the Background
FIG. 8 is a schematic diagram showing the construction of a main part of an electrophotographic apparatus for explaining an outline of its electrophotographic process. In the case as shown in FIG. 8, a photoconductive element 1 rotates in a counterclockwise direction (direction indicated by an arrow). The surface of the photoconductive element 1 is uniformly charged at a charge applying section 2 is well known, and a latent image is formed by being exposed by an optical writing section 3 which moves in accordance with the rotation of the photoconductive element 1. The photoconductive element 1 further rotates, and the element is developed by toner which selectively adheres onto the surface of the photoconductive element 1 corresponding to the latent image by a developing section 4, and thereby a toner image is formed. The toner image contacts a cut sheet 10 which is conveyed from a sheet feeding roller 11 and registration rollers pair 12 at a transfer section 5 in synchronizing with a predetermined timing, and that is transferred onto the cut sheet 10.
The toner image transferred on the cut sheet 10 is fixed thereon at a fixing section 6, and the cut sheet 10 having the fixed toner image thereon is discharged, as a hard copy, outside of the main body from a sheet discharging section 7.
Furthermore, the photoconductive element 1 has the toner or the like which is not completely transferred onto the sheet at the transfer section 5, and is collected at a cleaning section 8. The voltage on the surface of the photoconductive element 1 is made equal to approximately 0 volt at a discharging section 9 after the position on the surface of the photoconductive element 1 passes though the transfer section 5, the toner or the like which is not completely transferred onto the sheet at the transfer section 5 is withdrawn at a cleaning section 8. And then, aforementioned portion on the surface of the photoconductive element 1 returns to the charge applying charger section 2 once again. The photoconductive element 1 continuously forms a hardcopy by repeating the aforementioned series of operation.
FIG. 9 is a schematic diagram showing the entire construction of the electrophotographic apparatus to which the present invention is applied. In FIG. 9, a reference numeral 21 denotes a sheet feeding section of the main body (hereinafter called "main sheet feeder"), a reference numeral 22a a first optional sheet feeding section (optional sheet feeding section is hereinafter called "optional sheet feeder"), a reference numeral 22b a second optional feeder, and a reference numeral 22c a third optional sheet feeder.
FIG. 10 is a flow chart showing an example of a method of controlling a conventional electrophotographic apparatus. In the conventional electrophotographic apparatus, a photoconductive element drive motor (not shown) starts regardless of a kind of the selected feeder (main feeder or optional feeder), and the motor always starts when a page memory (a memory for individually storing image information for every one page in a bit-map format) is brought to a "Full" state. However, it takes long time for a recording sheet fed from the optional sheet feeder to reach a transfer nip K in comparison with a recording sheet fed from the main sheet feeder, for the reason that the sheet feeding distance from a sheet feeding start position to a transfer nip K of the optional sheet feeder is longer than that of a main sheet feeder, and further, in the case of using a roll sheet feeder, it takes much longer time to execute the paper feeding operation from a sheet feeding start position to another position of a transfer nip K where the recording paper reaches than in the case of using the main sheet feeder. The above matter occurs, because cutting operation of the recording sheet is needed in addition to the sheet feeding operation. Therefore, in the case of executing the above optional sheet feeding operation, the photoconductive element is rotated for much longer time than the necessary time in comparison with the case of feeding the sheets from the main sheet feeder. For this reason, for example, electrostatic fatigue or amount of physical wear of the photoconductive element in the case of executing the sheet feeding operation of the optional sheet feeder is much larger in comparison with the case of executing that of the main sheet feeder, and therefore, some problems to be solved in the lifetime of the photoconductive element and the drive system of the main body may happen on some occasions.
Therefore, the present invention is made in light of an above-mentioned problem.